1. Field of the Invention
The present invention relates to a data communication apparatus for transmitting and receiving image data and character code data.
2. Related Background Art
FIG. 1 shows an example of a constitution of a conventional facsimile apparatus.
Reference numeral 1 denotes a reader; 2 is a memory; 3 a printer; 4 a main unit; 5 an encode/decode unit; 6 a line control unit; 7 a control line; 8 to 12 image data lines; and 13 a packet switch network. The operation of a general facsimile apparatus of this conventional example will now be schematically explained.
Upon transmission, the reader 1 is actuated by the main unit 4 and the image data of the original which was photoelectrically read by the reader 1 is stored into the memory 2 through the data line 8. The stored image data is read out under control of the main unit 4 and supplied to the main unit 4 through the data line 10. This data is further transmitted to the encode/decode unit 5 through the data line 11. The transmitted data is encoded by the encode/decode unit 5 in response to a start signal from the control line 7. The encoded data is transmitted through the data line 12 and stored in a transmission buffer in the line control unit 6. The line control unit 6 adds a header to the buffer data on the basis of parameters and the like which are input from the control line 7 and transmits the buffer data onto the packet switch network 13 in a manner such that a proper data length is set to one frame. A data circuit terminating equipment (hereinafter, abbreviated to--DCE) serving as a connecting apparatus with a digital switch network is provided after the packet switch network 13 and connected to the distant apparatus through the switch network.
Upon reception, the image data input from the packet switch network 13 is stored in a reception buffer of the line control unit 6. The line control unit 6 informs the reception of the data to the main unit 4 through the control line 7, thereby actuating the encode/decode unit 5 and allowing the encoded image data which was received from the data line 12 to be decoded. The decoded data is supplied to the main unit 4 through the data line 11 and further written into the memory 2 from the data line 10. When a proper amount of image data has been stored into the memory 2, the printer 3 is made operative by a control signal from the control line 7. The image data is output to the printer through the data line 9 and the image is recorded and reproduced on a recording medium by the printer 3.
In such a conventional apparatus, one terminal is provided with one function as a reader and one function as a printer, so that the reception from a plurality of subscribers cannot be simultaneously performed, and the transmission to a plurality of subscribers cannot be simultaneously performed as well. In addition, there are the drawbacks such that even when the user wants to transmit, if the apparatus is in the receiving mode at this time, he must wait until the data reception is finished and the like, so that even if the line speed is high, this merit cannot be utilized as much as might be desired.